Subtract 42/84 from 1/21
1/21 - 42/84 is -19/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 84 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 21 × 4 = 84,
1/21 = 1 × 4/21 × 4 = 4/84 - Likewise, for the 2nd fraction, since 84 × 1 = 84,
42/84 = 42 × 1/84 × 1 = 42/84 - Subtract the two like fractions:
4/84 - 42/84 = 4 - 42/84 = -38/84 - After reducing the fraction, the answer is -19/42
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